[Alterations of smooth-pursuit ocular movements in Alzheimer's disease]

Recent findings suggest that patients affected by Alzheimer's disease (AD) have evident alterations of smooth-pursuit ocular movements induced by a sinusoidal predictable target. For a better understanding of the possible modifications of this performance in patients with AD we evaluated, using a quantitative method, the smooth-Pursuit induced by ramps with constant, unpredictable velocities. Twelve patients with probable AD were studied. These patients were compared with twelve age matched healthy volunteers. Visual inspection of our recordings shows that AD patients have frequent, large saccades intrusions which in some cases appeared to disrupt smooth tracking, particularly for low target speeds. Furthermore, the smooth-pursuit eye velocity induced by target of high speed is significantly reduced in respect to that present in our control group. Some significant correlations between altered smooth-pursuit parameters and abnormal psychometric scores were noted.